Dear

to calculate the effective mass of electron (or hole) in a given direction, you should first of all run scf and nscf calculations with a dense k pints grid. secondly, do band calculations in the given k direction. by using post processing tool you can get a *.dat file containing eigenvalues ordered in a manner that can be used by the origin software. from the graph e(k), you can dedeuce the effective mass as a second derivate or you can use e(k^2) (E=hk^2/2m).

best regards

It's not clear to me what the problem is, but the basic calculation you need is d2E_n/dk_i dk_j at the maximum or minimum of the band eigenvalue E_n, which gives the effective mass tensor, where i and j label the cartesian components of the k-point. Diagonalising this gives both the inverse effective masses (the eigenvalues of the effective mass tensor) and the directions of propagation (the eigenvectors).

You can do this yourself, or you can use an existing tool to do it, for example the Effective Mass Calculator:

https://github.com/afonari/emc